1. Field of the Invention
This invention relates to a liquid crystal display module, and more particularly to a liquid crystal display panel that is capable of preventing cracking of a light guide plate and light leakage.
2. Description of the Related Art
Generally, a liquid crystal display (LCD) includes a liquid crystal display module, driving circuitry for driving the liquid crystal display module, and a case.
The liquid crystal display module consists of a liquid crystal display panel having liquid crystal cells arranged in a matrix between two glass substrates, and a backlight unit for irradiating a light onto the liquid crystal display panel. The liquid crystal display module is arranged with optical sheets which vertically raise a light progressing from the backlight unit toward the liquid crystal display panel.
The liquid crystal display panel, the backlight unit and the optical sheets must be engaged with each other in an integral shape in order to prevent light loss. Likewise, the formation of the liquid crystal display panel, the backlight unit and the optical sheets as an integral shape protects the same from damage caused by external impacts. A case for the LCD enclosing the back light unit and the optical sheets including the edge of the liquid crystal display panel is provided in order to prevent light loss and damage to the LCD.
Referring to FIG. 1 and FIG. 2, a conventional liquid crystal display module includes a support main 14, a backlight unit and a liquid crystal display panel 6 disposed at an inside of the support main 14, and a case top 2 for enclosing the edge of the liquid crystal display panel 6 and the support main 14.
The liquid crystal display panel 6 comprises an upper substrate 3 and a lower substrate 5. A liquid crystal is injected between the upper substrate 3 and the lower substrate 5, and the liquid crystal display panel 6 is provided with a spacer (not shown) for maintaining a gap between the upper substrate 3 and the lower substrate 5. The upper substrate 3 of the liquid crystal display panel 6 is provided with a color filter, a common electrode and a black matrix, among other components. A signal wiring, such as a data line and a gate line, (not shown) or the like, is formed at the lower substrate 5 of the liquid crystal display panel 6, and a thin film transistor (TFT) is formed at an intersection between the data line and the gate line. The TFT switches a data signal to be transmitted from the data line into the liquid crystal cell in response to a scanning pulse (i.e., a gate pulse) from the gate line. A pixel electrode is formed at a pixel area between the data line and the gate line. One side of the lower substrate 5 is provided with pad areas connected to the data lines and the gate lines. A tape carrier package mounted with a driver integrated circuit for applying a driving signal to the TFT is attached onto a pad area of the pad areas. The tape carrier package applies data signals and scanning signals from the driver integrated circuit to the data lines and the gate lines, respectively.
An upper polarizing sheet 4a is attached to the upper substrate 3 of the liquid crystal display panel 6 while a lower polarizing sheet 4b is attached to the rear side of the lower substrate 5 of the liquid crystal display panel 6. The upper and lower polarizing sheets 4a and 4b enlarge a viewing angle of a picture displayed by a liquid crystal cell matrix.
The support main 14 is a molded product, and an inner side wall surface is molded into a stepped coverage face. An inner bottom layer of the support main 14 is mounted with a backlight unit including a reflective sheet 12, a light guide plate 10, a plurality of optical sheets 8 and a lamp housing (not shown).
As shown in FIG. 3, the backlight unit includes a lamp 20, a lamp housing (not shown) for enclosing the lamp 20, a light guide plate 10 which allows passage of light input from the lamp 20 into the liquid crystal display panel 6, a reflective sheet 12 arranged at a rear side of the light guide plate 10, and a plurality of optical sheets 8 disposed on the light guide plate 10.
A light generated from the lamp 20 is incident, via an incidence face defined at a side surface of the light guide plate 10, into the light guide plate 10. The lamp housing reflects a light from the lamp 20 into an incidence face of the light guide plate 10.
The reflective sheet 12 re-reflects a light incident thereto through the rear side of the light guide plate 10 into the light guide plate 10, thereby reducing light loss. In other words, if a light from the lamp 20 is incident to the light guide plate 10, then a light which traveled into a lower surface and the side surface of the light guide plate 10 is reflected by the reflective sheet 12 thereby traveling toward a front side thereof.
The light guide plate 10 converts a light input with the incidence face from the lamp 20 into a plane light source. The light guide plate 10 then outputs the light to the liquid crystal display panel 6.
The plurality of optical sheets 8 vertically raise a light output from the light guide plate 10, thereby improving light efficiency. Diffusing sheets are provided which diffuse light output from the light guide plate 10 into the entire area. Two prism sheets are also provided which raise a progress angle of the light diffused by the diffusing sheets vertically with respect to the liquid crystal display panel 6. Thus, a light output from the light guide plate 10 is incident, via the diffusing sheets and the plurality of optical sheets 8, to the liquid crystal display panel 6.
The case top 2 is formed in a square band shape having a plane part bent perpendicularly and a side part bent perpendicularly. The case top 2 encloses an edge of the liquid crystal display panel 6 and the support main 14.
In order to prevent breakage of the lamp 20 from shaking of the light guide plate 10, each side of the support main 14 and the light guide plate 10 has a stopper 30 for securing the light guide plate 10 as shown in FIG. 3 and FIG. 4. The stopper 30 has a convex step coverage 24 protruding from the side wall of the support main 14 into the light guide plate 10. The stopper 30 also has a concave step coverage 22 defined at each side surface of the light guide plate 10. Thus, the convex step coverage 24 formed at the support main 14 contacts the concave step coverage 22 of the light guide plate 10, thereby restraining the light guide plate. However, if a strong impact is applied to the support main 14 or the light guide plate 10, the impact transfers to the concave step coverage 22 of the light guide plate 10 thereby generating a crack 26 at the light guide plate 10 as shown in FIG. 4. The crack 26 causes light leakage.
In order to minimize the generation of the crack 26, each corner of the concave step coverage 22 of the light guide plate 10 and the stopper 30 has a rounding R. The rounding R has a rounded shape as shown in FIG. 4. However, since the concave step coverage 22 of the light guide plate 10 is joined with the convex step coverage 24 of the support main 14, a friction on the support main 14 is produced when the rounding R of the concave step coverage 22 is large thereby causing noise.
Furthermore, in conventional liquid crystal modules, each edge of the light guide plate is darker than other portion thereof due to the concave step coverage 22 of the light guide plate 10.